(a) Field of the Invention
The present invention relates to a method of manufacturing a liquid crystal display. More particularly, the present invention relates to a method of manufacturing a liquid crystal display using an ion beam alignment method.
(b) Description of the Related Art
A liquid crystal display (“LCD”) is a widely used display device. It typically includes two display panels on which field generation electrodes are formed and a liquid crystal layer interposed therebetween. Varying amounts of light are then selectively transmitted through the display by controlling alignment of liquid crystal molecules of the liquid crystal layer by applying a voltage to the field generation electrodes.
Although LCDs have a drawback of a narrow viewing angle due to optical anisotropy of liquid crystal molecules, the LCD realizes a wide viewing angle through development of an optically compensated bend (“OCB”) mode, an in-plain switching (“IPS”) mode and various vertically aligned modes using a plurality of domains. The plurality of domains may be formed by artificially distorting an electric field.
As a means of forming a plurality of domains, a protrusion or a cutout in a field generation electrode may be used. In operation, as liquid crystal molecules are aligned in a direction perpendicular to a fringe field formed between an edge of a protrusion or a cutout and a field generation electrode that is opposite thereto, a plurality of domains are formed. However, because a process of forming a protrusion or a cutout is difficult and complicated, the manufacturing cost of the display device increases, and furthermore, the plurality of cutouts or protrusions decreases an aperture ratio of the display.
Furthermore, although liquid crystal molecules that are positioned adjacent to a protrusion or a cutout can be easily aligned in a direction perpendicular to a fringe field, a random motion occurs in liquid crystal molecules that are positioned at a central part that is relatively far away from the cutout, and therefore the response speed becomes slow and a backward direction domain is formed, whereby an afterimage may be displayed.
As a means of forming a plurality of domains in one pixel, an alignment layer that controls an alignment direction and an alignment angle of liquid crystal molecules by radiating light or ions to an organic or inorganic layer may be used. In operation, because it is unnecessary to form a protrusion or a cutout in a field generation electrode the aperture ratio can be increased, and by generating a pretilt angle with the alignment layer, the response speed of the liquid crystal molecules can be increased.
However, the method of forming an alignment layer with light is a method of forming a plurality of domains by radiating ultraviolet rays (UV) in a plurality of directions in every pixel on a surface of an organic layer on a substrate, and the method of forming an alignment layer with an ion beam is a method of forming a plurality of domains by radiating an ion beam in a plurality of directions in every pixel on a surface of an inorganic layer that is formed on a substrate.
However, in the method of forming the alignment layer with light, because an afterimage problem due to an uncured organic material component exists and anchoring energy sequentially becomes weak, initial alignment of the liquid crystal molecules may be somewhat random. A mask is used when forming a plurality of domains using light or an ion beam, and in this case, at a border portion of the mask, an alignment failure region at which light or an ion beam (which may be Ar ions) is indirectly radiated is generated. If the alignment failure region is not completely blocked by a light blocking member, a display failure is generated. A display failure according to an alignment failure region can be checked by testing a liquid crystal molecule alignment state after manufacturing the liquid crystal display, as shown in FIG. 16.